Surgical efforts to repair cranial defects commonly occur. For example, various types of surgical procedures on the human brain require removal of a portion of the skull. By way of example only, those include surgeries that remove brain tumors, surgeries to reduce brain swelling, and surgeries required to reconstruct damaged portions of the skull.
In many of these surgeries it is of course most desirable that when the successful surgery is completed that the patients own skull plate be returned intact. There are many occasions however where this is simply not possible. Perhaps the most common example is those instances where there are good medical reasons why the removed skull plate needs to be stored for long periods of time. A typical example would be with brain swelling that is relieved by removal of a portion of the skull. This may necessitate a long time between removal and replacement. In typical procedures where skull portions are removed, they must be replaced within an eight week period or the infection risk becomes too high. Therefore the removed skull plate simply cannot be returned.
In those cases that the skull plate cannot be returned, either because it has been removed for such a prolonged period or because it has been damaged, it is necessary to insert an artificial skull plate. Such artificial skull plates are normally prepared on the spot in surgery using a plastic resinous material that is moldable for a brief period and then sets. A typical example of such a material is one sold under the trademark, CRANIOPLASTIC, by the L. D. Caulk Co., Division of Dentsply International Inc., of Milford, Del. 19963.
These resinous materials for repairing cranial defects generally consist of a powder component and a liquid component. They are maintained in sterile condition and mixed during the course of the surgery. After mixing the two monomers there is a doughing time during which kneading occurs, perhaps four to five minutes, at which time the material becomes dough like and capable of handling for a period that varies depending upon temperature, but usually for about six to eight minutes. During a typical operation the surgeon hand molds the material during this period of time followed by a setting time of thirteen to fifteen minutes. In this brief period of time the physician, by hand, molds the prosthesis to conform to the cavity in the skull as best he can, it sets, and then he may have to further alter it by grinding, and the prosthesis is then sutured into the skull.
Obviously under the pressure of surgery and by use of the hand technique, it is impossible for the surgeon to obtain precise conformity with the skull cavity left by removal of the patient's own cranial plate. Thus, at best, even the most skilled surgeons can provide only an approximation of conformity. Moreover, with time pressure between the doughing period and the setting period. The surgeon must work as fast as possible under the constant pressure of the knowledge that if he does not complete his work within six to eight minutes the material will set and become unworkable. When this occurs another attempt must be made to provide a satisfactory prosthesis.
As a result of the above situation confronting surgeons during cranioplasty surgery, two common results occur. In the first instance in almost all cases the prosthetic skull plate is at best an approximation to the patient's excised skull plate. In the second instance, time in the operating room is lengthened considerably because of the time involved in the hand formation of the skull plate, the time involved in setting of the plate, and if there are failures, the time involved in repeating the process. At typical surgical room hourly billing rates one can see that the expense is considerable. Moreover, since there are approximately 60 to 80 thousand of these procedures that occur annually, it can be seen that the increased expense is enormous. Moreover the resulting prosthesis is often a very poor duplication of the removed patient's cranial plate. This of course means that the fit is imperfect, which may cause its own subsequent patient problems.
Accordingly, it is an object of this present invention to provide an improvement in the cranioplasty surgical procedure, wherein operating time is reduced and as well an excised portion of a patient's skull can be replaced with a virtual duplicate of the patient's removed cranial plate.
Another object of the present invention is to provide a process for making a reproduction of excised portion of a patient's skull, utilizing an impression material in conjunction with a resinous CRANIOPLASTIC material.
Another object of the present invention is to provide a kit usable in conjunction with cranioplasty surgery, which contains a sterile resinous material portion for repairing cranial defects and separately packaged an impression material usable for making a 3-dimensional mold cavity of an excised portion of a patient's skull, and finally, instructions for use of the two materials to provide duplication of the patient's removed skull portion.
The method and manner of accomplishing each of the above objectives will become apparent from the detailed description of the invention which follows hereafter.